Javascript image hover doohicky.

Hello everyone. So I am trying to build a small website for a school project. The website is going to be aboot two legislators and in the menu section I want to be able to hover the mouse over the name/link and have an image of them appear...

Here is an example of what I need. I looked through the source of this site and could not isolate the right code.
I think it has something to do with prototip.js but it's really jumbled.
http://www.grenchen.net/blog/index.php

I want it to look like the image on that site(how it moves with the mouse and works really nicely) but it will be when the mouse goes over the text not an image...

Any help is welcome, even another similar script. I've seriously spent aboot 30 minutes searching Google for something similar and another 30 looking through the source of the above mentioned website...

"The definition of insanity is doing the same thing over and over again and expecting different results.”
~Albert Einstein~